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While certain kinds of metal fabrication can only be done in a professional shop, others are easily accessible to the enthusiastic DIYer. A metal lathe is easier to use than it might seem, once you get the terminology down. Learn about the different operations you can perform with a lathe, as well as some common projects and safety tips.
- What Is a Metal Lathe?
- Types of Metal Lathe
- Metal Lathe Terminology
- Metal Lathe Uses
- How to Use a Metal Lathe
- Safety Precautions for Using Metal Lathes
What Is a Metal Lathe?
A metal lathe is a piece of machinery that holds and turns metallic objects. The rotational force is interrupted by various tools, removing material and allowing the metal to be shaped and formed.
For their price, lathes are highly useful and can help you on a variety of projects.
Types of Metal Lathe
There are three terms used to refer to metal lathes; turret, special purpose, and engine.
Turret lathes are large, stationary lathes, and are typically used to mass produce fabricated metal. They are rarely used outside of professional/industrial contexts.
Special Purpose Lathe
When a specific part must be manufactured in high quantities, machine shops or manufacturers will sometimes engineer a lathe that accomplishes one single purpose.
Engine lathes are smaller than turret lathes and are semi-portable. They can be free-standing or bench mounted. Used for a variety of projects, from machine part fabrication to jewelry-making, most lathe work is completed on an engine lathe.
‘Mini’ metal lathes are the smallest available engine lathes. Most consumer metal lathing is done on mini engine lathes. When used properly, they are perfectly safe, and the range of projects you can complete with an engine lathe is virtually endless.
For an in-between option, try out the best midi lathe.
Some of the most popular metal lathe projects are:
- Rings and other jewelry
- Custom screws
Metal Lathe Terminology
There’s a fair amount of specialized terminology that you need to wrap your brain around before understanding how to operate a lathe.
Headstock and Tailstock
The two most important parts of your lathe are the headstock and the tailstock. The headstock is always on the left-hand side. A motor and pulley system turns the headstock, along with whatever is attached to it. The headstock does not move from side to side.
The tailstock is located on the right-hand side of the lathe. It slides back and forth on the bed rails. This allows it to be closer to the headstock for smaller projects, or further away when a larger piece of metal is being turned.
The headstock and tailstock are connected by the bed and bed rails. The tailstock slides along the bed rails. The workpiece is suspended over the bed of the lathe, between the headstock and tailstock.
The spindle is a rod in the center of the headstock. Attachments can be threaded directly onto the spindle, or it can be used to hold a secondary part such as a chuck. The chuck then holds the workpiece, enabling the spindle, chuck, and metal to spin as one unit.
The ‘swing’ of a metal lathe gives you information about the size of workpieces it can handle. In other words, the swing is the maximum diameter workpiece your lathe can handle.
For the lathe to operate as designed, the workpiece must be able to rotate freely, without encountering any other part of the machine. This range of motion is limited by the distance between the center of the workpiece and the bed of the lathe.
- A lightweight bench or table top metal lathe has a swing of ten inches or less.
- A standard manufacturing metal lathe has a swing of up to 25 inches.
- Workpieces wider than 25 inches require the use of an adjustable gap or extension-type lathe.
Metal Lathe Uses
The basic purpose of a metal lathe is to produce cylindrical metal stock, but that’s not all they can do. You can also machine metal in various ways.
Facing metal stock means getting it even, square, and ready to be centered in the headstock. It is generally the first step of machining metal in a lathe.
When you need a hole in the bottom of a metal cylinder, you can get a smooth, perfectly centered, round hole by using a metal lathe. To drill using a lathe, the tailstock must be equipped with a center drill, or a boring bar.
A round-shaped die can be used to create threads in a cylinder of metal. When cleaning up existing thread, a hex-shaped die is often the tool of choice.
Tapping is the process of adding threads to a previously drilled hole. Metal lathes accomplish this with the help of special tools called taps. Spiral flute taps and spiral point taps are the most common tools used for this purpose.
To remove metal and shape the workpiece, turning tools are used. Sharp-ended objects are introduced to the spinning metal and shave pieces off, decreasing the total size of the workpiece and changing its shape.
In tapering, a portion of the metal blank is shaped to resemble a cone. Tapering can be ornamental, as in the case of candlesticks, or mechanical, allowing two parts to fit snugly together.
Chamfering is the process of creating a sloped, symmetrical edge in place of a sharp, right-angled corner. It is the first step in the process of changing square stock into a cylinder.
Cutting or Parting
Parting or cutting tools are used to separate the workpiece from excess metal above or below it.
Knurling is the process of rolling lines into metal. The lines can be straight, angled, or crossed. Different knurling tools are used to achieve various knurled effects.
How to Use a Metal Lathe
Now that you have an idea of what metal lathes can do, follow these basic steps to get started with your next project.
- Protect yourself. At minimum, put on eye protection and remove anything that could get caught in the lathe. Hearing protection is important, too. A high necked shirt and shop apron will protect you from metal shavings and sparks.
- Perform routine maintenance. Any tools you’re working with should be sharp. The bearings of your headstock should be well-lubricated, and your oil reservoir should be full. Get into the habit of checking these things before each use.
- Insert the stock. Based on what operation you want to carry out, select an appropriate device to attach the metal blank to the headstock. This could be a chuck, collet, faceplate, mandrel, center, or drive plate. Line the center of the stock up appropriately and secure it in the lathe.
- Check the swing. Before going any further, spin the lathe once by hand. The metal stock should rotate cleanly and evenly, without any wobbling, unevenness, or scraping.
- Lay out your tools. In some lathe operations, such as drilling or tapping, the tool is attached to the tailstock. In others, such as chamfering, turning, or taperting, the tool rests parallel to the work pieces. Whatever you’re trying to achieve, make sure you have the relevant tools set up.
- Make your markings. Use a permanent marker or other marking tool to mark material for removal.
- Adjust the tool rest. Move the tool rest to allow you to access the appropriate section of the workpiece. Spring the workpiece after adjusting the tool rest to make sure there is appropriate clearance between the tool rest and the metal workpiece.
- Get started. Set the speed of the spindle, and turn the machine on. If the operation you are performing requires a handheld tool, rest the tool on the tool rest. Angle it appropriately, and slowly introduce it to the spinning metal. If the tool is attached to the tailstock, move the tailstock along the rails to introduce it to the workpiece. Allow the tool to remove material and shape the metal.
- Take a break. Turn the lathe off and wait for it to stop spinning. Visually inspect the workpiece and take any necessary measurements. Take note of the stock alignment and make any necessary adjustments.
- Continue turning. Machine the material using the tools of your choice, to produce your desired result. Cutting fluid can be used to reduce heat, deter rust, clear chips, increase the life of your cutting tool, and to create a smoother finish. Pay attention to the lathe vibrations and try to keep chatter to a minimum.
Safety Precautions for Using Metal Lathes
Working with lathes is relatively safe as long as the relevant protective precautions are observed. A few things to keep in mind when preparing to use a lathe:
- Remove rings, watches, and bracelets.
- Roll sleeves out of the way – above the elbow.
- When chuck keys or wrenches are used to adjust the lathe, remove them before turning on the machine.
- Never place tools on the lathe bed. Use a separate table, if possible.
- Remove metal chips or debris with tools like a brush. Don’t risk cutting your hands.
- Do not lean on a lathe
- Wait until the work has stopped spinning to measure it.
- Always wear eye protection.
Metal lathes are capable of shaping and manipulating metal in dozens of ways. The tools you use when turning metal on a lathe affect the outcome of the workpieces. Safe operation of a lathe includes keeping a safe distance, wearing protective equipment, and knowing how the lathe works.